Why a 200 MB text file overloads 4gB ramAnd to answer the other part of your question, I really do not know why gedit uses that much memory -- may be partly due to bad programming, or a bug. I don't see any reason why it should. If you want the least memory intensive way to view a huge file, I think less is the only way to go, from my digging ( you can't edit it in that case, though )